Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

Annotations already declare readOnlyHint, idempotentHint, destructiveHint=false and openWorldHint=false, so the safety profile is covered. The description adds genuine context beyond that: it labels the call 'Informational only' and corrects the likely misreading of 'area' as a radius/distance, which is a real behavioral clarification.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

Three tight sentences, front-loaded with what is returned, then the semantic caveat, then the routing tie-in. No filler and nothing repeated from the schema or annotations.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

An output schema exists and the description still names the key fields, so return-shape explanation is not required. For a zero-parameter, read-only listing tool this covers everything an agent needs before calling it.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Zero parameters, so the baseline is 4. The description goes slightly beyond by explaining that the emitted slug is the value accepted by search_objectives' area parameter, giving the output field cross-tool meaning rather than leaving it as an opaque identifier.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

States a specific verb and resource ('Lists the public coverage areas shown on the coverage directory') and enumerates the returned fields (slug, name, state/province code, visible activities). It also disambiguates the domain term against its nearest sibling by tying the slug to search_objectives' optional area input.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

Clarifies the operating context with 'An area is a fixed geographic definition, not a distance from the caller' and 'Informational only', and points at search_objectives as the consumer of the slugs. It gives clear context but stops short of an explicit when-to-use / when-not-to-use rule against the other siblings.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.